Apparatus for indicating the rise of liquid in a mold

ABSTRACT

A refractory float is adapted to float on liquid metal in a mold and is connected to a rotatably mounted winding drum by a flexible connecting element, which is adapted to be wound up on said drum and to be unwound therefrom by a rotation of said drum. Drum-driving means are operatively connected to said drum and arranged normally to exert on said drum a torque which is insufficient to raise said float when the same is supported only by said flexible connecting element and which is sufficient to maintain said flexible connecting element taut when said float is supported by means other than said flexible connecting element. A transducer is provided as well as means operatively connecting the transducer to the drum. The transducer is operable to produce an electric output signal in response to an angular movement of said drum. Signal-utilizing means are connected to said transducer and responsive to said output signal.

United States Patent n51 3,685,358 Hubner et al. [4 1 Aug. 22, 1972 [541APPARATUS FOR INDICA'IING THE 3,459,042 8/1969 Brown ..73I32l RISE OFLIQUID IN A MOLD Pn'mary MMTI.DUI8 R. Prince [72] Inventors. lJanzinzBuzzing, Writer .Iilelr, both of MM Mmr-Danid M. Yasich Attomey-KurtKelman [73] Assignec: Vereinigte Beenund Stahlwel'ke 57 mm Ausma Arefractory float is adapted to float on liquid metal in [22] Wed: a moldand is connected to a rotatably mounted wind- 21 Appl, 4 ,917 ing drumby a flexible connecting element. which isadaptedtobewounduponsaiddrumandtobeunwound therefrom by a rotation ofsaid drum. Drum- [30] Fomgn Application m M driving means areoperatively connected to said drum June 18, 1969 Austria ..A 5750/69 andarranged normally to exert on said drum a torque which is insulficientto raise said float when the same [52] US. Cl ..73/32I, 33/ 126.6 issupported only by said flexible connecting element [5 I] IIII. CI l0 andwhich is suflicienl m said. flgxible gon. [58] FICIIIOISGQNII "73/321;33/126.6 R necfing elgment taut when said float suppoflgd by means otherthan said flexible connecting element. A [56] Refmum W transducer isprovided as well as means operatively UNITED STATES PATENTS connectingthe UfiIlSdUOCI' ID the TIN transducer is operable to produce anelectric output signal 3,546,94I in response to an myg nent of 3,090,2325/ 1963 Signal-utilizing means are connected to said transducer andresmnsive m oupu signal 3,099,158 7/1963 Barker, Jr ..73/32l 3,l28,5574/1964 Childs ..33/l26.6 X 11 Chins, 2 Drawing Figures PATENTEB I9723.685.358

FIG]

INVENTORS IRAs-l. uuIn NHLTEI. igglk APPARATUS FOR INDICATING THE REE FLIQUID IN A M011) This invention relates to apparatus for mesuring therising speed of liquid metal in molds and the like, particularly iningot molds, as the metal is poured into the mold.

When molten metal and particularly steel is poured into ingot molds orother molds, the rising speed of the metal in the mold depends on thepouring rate and exerts a strong influence on the solidification andsurface finish of the cast product. For this reason it is desired incasting operations, particularly in the casting of steel, to control thepouring rate and rising speed at the values which are optimum in view ofthe kind of steel being cast, the temperature of the steel. and thecrosssection of the ingot mold or other mold, and to maintain saidpouring rate and rising speed constant at said values throughout thepouring or to vary them in an exactly controlled manner in accordancewith certain rules, which may have been established as a result ofexperience. Particularly in bottom pouring operations, in which themolten metal enters the ingot mold or other mold at the bottom thereof,the rising speed should be exactly maintained at a predetermined orpreselected value.

In the previous practice, the rising speed of the metals during thepouring operation is empirically set. It will be understood that thispractice involves large deviations from the rising speed which would beoptimum for the respective operation. An improvement has been providedin that weighing devices have been incorporated in the ladle crane sothat the amount of metal poured in a predetermined time can be exactlychecked. Because the size of the mold is approximately known, the risingspeed can be controlled in view of the result of such check. lt has beenfound, however, that crane balances will not operate satisfactorilyunless they are incorporated in new cranes. The incorporation of cranebalances into existing cranes involves structural difficulties, whichcontinually result in disturbances of the balances so that this indirectmeasurement of the rising speed of liquid metals being poured cannot beadopted in old steelworks. Besides, the balances are highly expensiveand liable to be deranged by the rough usage in a steel-making plant.

To control the capacity of the pump for discharging a crucible formelting metals so that the rate at which metal is discharged by the pumpremains constant independently of the level of the bath, it is known toprovide a refractory float, which operates a rod that extends out of thecrucible and at its upper end carries a rack, which is operativelyconnected to a regulating valve included in a compressed-air conduitleading to a compressed-air motor which drives the discharge pump. Thisvalve is thus controlled by the float, which must exert the forcesrequired to operate the valve. The various forces applied to the floatmay cause the latter to rise irregularly or suddenly. This arrangementserves only for a coarse control of a motor whereas there is nomeasurement of the level of the bath or of the speed at which said levelsubsides. The arrangement cannot be used in conjunction with a pluralityof molds or the like because it is stationary, also because inaccuratemeasurements would have to be expected and because the transmittinglinkage is bulky.

It is an object of the invention to provide a simple apparatus formeasuring the rising speed of liquid metals in molds or the like,particularly in ingot molds, which apparatus may also be used, ifdesired, for a direct or indirect control of the pouring operation andcan easily be used in conjunction with a plurality of different ingotmolds or other molds in succession.

The apparatus according to the invention is of the kind defined firsthereinbefore and comprises a refractory float, which floats on theliquid metal and is operatively connected to a transducer, which isoperated by the float and in which the level or the rising speed of thefloat is converted into a signal which can be sensed electrically orelectronically. The invention resides in that the float is connected bya flexible connecting element, such as a cable or wire, to a windingdrum, which is adapted to be driven by a spring or by a motoroperatively connected to the drum by torque-limiting means, and the drumis operatively connected by a transmission to the transducer, whichconsists of a generator or potentiometer, the torque which is exerted onthe drum by the spring or the torque-limiting means is smaller than thetorque required to freely raise the float, so that the transducer isadapted to be controlled by the drum in dependence on the level of thefloat and can be driven only during a movement of the float in responseto a change of the level of the liquid metal supporting the float,whereas the flexible connecting element secured to the float is heldtaut.

[n the apparatus according to the invention, a major portion of theforces required to move the float and drive the transducer are producedby the additional drive means so that very small control forces exertedby the float will be sufficient to produce the desired control orindication. This fact enables an exact indication of the level andrising speed of the float exactly in dependence on the level of themetal. Due to the use of the flexible connecting element, the apparatusis handy and can easily be moved from one mold to another when theconnecting element is wound up.

The transducer may consist of an alternating-current generator, which isadapted to be driven by a speed-increasing transmission and the outputof which is connected by a rectifier and, if desired, by a voltageamplifier, to an indicating or recording apparatus. Alternatively, thetransducer may consist of a potentiometer, which is connected to asource of constant voltage and which is adjustable in response to amovement of the float and connected to an operational amplifier,integrator and analog-digital converter or to a movingcoil recorderhaving a driven chart so that the vertical deflection performed by thestylus in response to the potentiometer and the feeding speed of thechart result in a recording of the rising speed of the metal in themold.

A converter may be provided which delivers pulses at a rate which isproportional to the rising speed. A simple converter for this purposemay consist of an interrupter, which is arranged to be driven by thespringloaded drum. This interrupter may consist of a mechanicalinterrupter having an interrupter contact which is operated by a gear,or of an optical interrupter consisting, e.g., of a hole disc forinterrupting a light beam of a photo-electric device. Alternatively, theinterrupter may consist of a piezoelectric transducer.

in a preferred embodiment, the transducer and the drive means or thelike are accommodated in a closed refractory housing, which can besecured to a wall of the ingot mold and from which the wire or the likeextends which holds the float. ln this case, the apparatus can easily bemoved from one ingot mold or other mold to the next.

The invention is shown by way of example on the aceompanying drawing, inwhich FIG. 1 is a sectional view taken on line ll of FIG. 2 and showingan apparatus according to the invention, and

FIG. 2 is a top plan view showing the apparatus with the housing in anopen condition.

The entire measuring apparatus 1 is supported by the wall 2 of an ingotmold and is detachably secured by means of holders 3, 4 and a fixingdevice 5 consisting of a set screw. The apparatus comprises a refractoryfloat 7, which floats on the surface of liquid metal which has beenpoured into the mold 2 so that the float rises during the pouringoperation at the same speed as the metal in the mold. A cable or wire 8is secured to the float by means which are not shown and is trainedaround a deflecting roller 9 and connected to a springloaded drum 10.

One end of a spiral spring 11 is secured to the springloaded drum 10, onwhich the wire 8 can'be wound. The other end of the spring 11 is rigidlyconnected to an axle 12, on which the drum 10 is rotatably mounted, sothat the spring 11 is stressed as the wire 8 is unwound. The wire 8 isunwound when the float 7 is lowered to the bottom of the ingot mold orother mold before a measuring operation. The spring force is selected sothat it can constantly maintain the wire 8 in a taut condition and candrive a transducer which in the embodiment shown by way of exampleconsists of an a.c. generator connected to the drum by a transmission13, whereas the spring cannot raise the float 7 as long as it is freelysuspended from the wire.

The transmission 13 is a speed-increasing transmission and consists of apinion or friction wheel 14, which is adapted to be driven by the springdrum 10, a gear 15 and another pinion 16. The pinion 16 is operativelyconnected by a clutch 17 to the alternating-current generator 18.

The alternating current generated by the alternatingcurrent generator 18is rectified by a rectifier l9 and fed to an indicating device 21 whichutilizes the rectified signal to indicate the rise of the liquid metalin the mold. An optional voltage amplifier is connected by an input lead22 to the rectifier l9 and by an output lead 23 to the indicating device21. Another lead 24 may be provided to apply the output voltage of thegenerator to a recorder or to a control device for controlling thepouring operation, the recorder utilizing the rectified signal to recordthe rise of the liquid metal in the mold and the control deviceutilizing the signal to control the pouring operation. The outputvoltage of the generator may be suitably transformed for this purpose.The control device for controlling the pouring operation may be arrangedto maintain the rising speed at a desired value in response to thesignal transmitted in lead 24. The indicating device and the 6 recorderare preferably calibrated to indicate the pouring rate or the risingspeed of the metal in the ingot mold or other mold.

The entire apparatus is accommodated in'a housing 25, which is providedwith a carrying handle 26 so that it can be transported to any ingotmold or other mold where it is required.

An embodiment has been described hereinbefore by way of example withreference to the drawing and may be modified as has been outlinedhereinbefore.

What is claimed is:

1. Apparatus for indicating the rise of liquid metal in a mold, whichapparatus comprises a refractory float adapted to float on liquid metalin a mold,

a rotatably mounted winding drum,

a flexible connecting element which is connected to said float and tosaid drum and adapted to be wound up on and unwound therefrom by arotation of said drum,

drum-driving means operatively connected to said drum and selectednormally to exert on said drum a torque which is insufficient to raisesaid float when the same is supported only by said flexible connectingelement and which is sufficient to maintain said flexible connectingelement taut when said float is supported by the liquid metal in themold,

a transducer comprising an alternating-current generator operable toproduce an a.c. output signal in response to an angular movement of saida speed-increasing transmission mechanically connecting said generatorto said drum whereby the output signal is representative of the speed ofsaid .a signal-utilizing means comprising indicating means connected tosaid generator and responsive to said output signal, and

a rectifier arranged between the generator and the signal-utilizingmeans to convert said a.c. signal into a dc signal.

2. Apparatus as set forth in claim 1, in which said flexible connectingelement consists of wire.

3. Apparatus as set forth in claim 1, in which said flexible connectingelement consists of a cable.

4. Apparatus as set forth in claim 1, in which said drum-driving meanscomprise a torsion spring connected to said drum and arranged to betorsionally stressed as said flexible connecting element is unwound fromsaid drum and to exert on said drum a torque which is insufficient toraise said float when said flexible connecting element has been entirelyunwound from said drum and said float is supported only by said flexibleconnecting element.

5. Apparatus as set forth in claim 1, in which said signal-utilin'ngmeans comprise a voltage amplifier operable to amplify said d.c. signal.

6. Apparatus as set forth in claim 1, in which said signal-utilizingmeans comprise an indicating device operable to indicate said do.signal.

7. Apparatus as set forth in claim 1, in which said signal-utilizingmeans comprise a recorder operable to record said d.c. signal.

8. Apparatus as set forth in claim 1, in which said transducer comprisesa constant-voltage source and a potentiometer connected to saidconstant-voltage source and mechanically connected to said drum andarranged to convert an angular movement of means adapted to utilize saiddigital signal. said drum into a change of voltage representing 10.Apparatus as set forth in claim 8, in which said said output signal.signal-utilizing means comprise a moving-coil recorder 9. Apparatus asset forth in claim 8, in which said connected to said potentiometer andresponsive to said signal-utilizing means comprise: 5 change of voltage.

an operational amplifier connected to said poten- 1 Apparatus as forthI11 Clalm WhlCh tiometer and responsive to said change of voltage Saidtransducer, Said drum, and said 9 p to produce an amplified i l, tivelyconnecting said transducer to said drum are an integrator connected tosaid amplifier and operacontain closed f gi ble to integrate saidamplified signal to produce an m means e P for fixmg Sald housing to aWallintegrated analog signal, f an analogdigiml Convener connected tosaid said flexible connecting element extends out of said tegrator andoperable to convert said integrated housmg to floatanalog signal into adigital signal, and 5

1. Apparatus for indicating the rise of liquid metal in a mold, whichapparatus comprises a refractory float adapted to float on liquid metalin a mold, a rotatably mounted winding drum, a flexible connectingelement which is connected to said float and to said drum and adapted tobe wound up on and unwound therefrom by a rotation of said drum,drum-driving means operatively connected to said drum and selectednormally to exert on said drum a torque which is insufficient to raisesaid float when the same is supported only by said flexible connectingelement and which is sufficient to maintain said flexible connectingelement taut when said float is supported by the liquid metal in themold, a transducer comprising an alternating-current generator operableto produce an a.c. output signal in response to an angular movement ofsaid drum, a speed-increasing transmission mechanically connecting saidgenerator to said drum whereby the output signal is representative ofthe speed of said drum, a signal-utilizing means comprising indicatingmeans connected to said generator and responsive to said output signal,and a rectifier arranged between the generator and the signalutilizingmeans to convert said a.c. signal into a d.c. signal.
 2. Apparatus asset forth in claim 1, in which said flexible connecting element consistsof wire.
 3. Apparatus as set forth in claim 1, in which said flexibleconnecting element consists of a cable.
 4. Apparatus as set forth inclaim 1, in which said drum-driving means comprise a torsion springconnected to said drum and arranged to be torsionally stressed as saidflexible connecting element is unwound from said drum and to exert onsaid drum a torque which is insufficient to raise said float when saidflexible connecting element has been entirely unwound from said drum andsaid float is supported only by said flexible connecting element. 5.Apparatus as set forth in claim 1, in which said signal-utilizing meanscomprise a voltage amplifier operable to amplify said d.c. signal. 6.Apparatus as set forth in claim 1, in which said signal-utilizing meanscomprise an indicating device operable to indicate said d.c. signal. 7.Apparatus as set forth in claim 1, in which said signal-utilizing meanscomprise a recorder operable to record said d.c. signal.
 8. Apparatus asset forth in claim 1, in which said transducer comprises aconstant-voltage source and a potentiometer connected to saidconstant-voltage source and mechanically connected to said drum andarranged to convert an angular movement of said drum into a change ofvoltage representing said output signal.
 9. Apparatus as set forth inclaim 8, in which said signal-utilizing means comprise: an operationalamplifier connected to said potentiometer and responsive to said changeof voltage to produce an amplified signal, an integrator connected tosaid amplifier and operable to integrate said amplified signal toproduce an integrated analog signal, an analog-digital converterconnected to said integrator and operable to convert said integratedanalog signal into a digital signal, and means adapted to utilize saiddigital signal.
 10. Apparatus as set forth in claim 8, in which saidsignal-utilizing means comprise a moving-coil recorder connected to saidpotentiometer and responsive to said change of voltage.
 11. Apparatus asset forth in claim 1, in which said transducer, said drum, and saidmeans operatively connecting said transducer to said drum are containedin a closed housing, means are provided for fixing said housing to awall, and said flexible connecting element extends out of said housingto said float.